Radiation Therapy for Optic Nerve Sheath Meningiomas: An Updated Systematic Review and Meta-analysis of 2,085 Patients

Introduction: Optic Nerve Sheath Meningiomas (ONSMs) represent about 2% of all orbital tumors. Despite the rare and benign nature of ONSMs, their location in a confined space and progressive growth over time can threaten overall visual function. Radiotherapy (RT) has emerged as a noninvasive treatment option for its potential impact on maintaining and improving visual outcomes. Herein, we performed an updated meta-analysis evaluating the efficacy and safety of RT for ONSMs.

Methods: We performed a comprehensive literature search using PubMed, Embase, and the Cochrane Library from inception to August 2024. Articles describing the use of RT for ONSMs were included. RT modalities of interest included 2-dimensional (2-D) RT, 3D-conformal RT, fractionated stereotactic radiation therapy (FSRT), stereotactic radiosurgery (SRS), intensity-modulated radiation therapy (IMRT), hypofractionated radiotherapy, and proton beam therapy (PBT).

Results: A total of 3,381 articles were retrieved, of which 61 studies encompassing 2,085 patients were included. The mean follow-up time was 47 months (range: 23-153). The overall tumor local control rate was 96% (95% CI, 91 to 99%; I2 = 84%). Local control with FSRT was 99% (95% CI, 96% to 100%; I2 = 68%), whereas SRS achieved 98% (95% CI, 93% to 100%; I2 = 40%). At the last follow-up, the estimated visual acuity stability or improvement rate was 85% (95% CI, 78% to 90%; I2 = 83%), and visual field stability or improvement rate was 88% (95% CI, 81% to 93%; I2 = 71%). The incidence of orbital pain was 0.03 (95% CI, 0.00–0.07; I² = 59%), optic neuritis was 0.01 (95% CI, 0.00–0.03; I² = 0%), and cataract formation was 0.05 (95% CI, 0.01–0.10; I² = 67%).

Conclusion : Our findings suggest that RT achieves high tumor control and contributes to preserving visual function. Notably, the low complication rates further underscore its safety profile. However, as advancements in RT evolve, ongoing research will be essential to refine treatment protocols.